This new program-project proposal reflects the next step in a unique, productive, and important program of research that spans comparative psychology, cognitive psychology, developmental psychology, and neuropsychology. Funding from NICHD serves as the majority means of support for the research at the Language Research Center at Georgia State University, a world-renowned resource for the study of language and cognition across primate species. A colony of unique and wonderful animals have been raised, trained, maintained and tested with NICHD support to communicate and to comprehend, to count and to perform elementary combinatorial operations, and to demonstrate a range of other cognitive abilities that make them singularly suitable for comparison to human adults and children. The historical antecedents of the present proposal are outlined below. In the eartier funding cycles at the Language Research Center, scientists examined the degree to which apes could acquire human-like language. They further explored the applicability of principles derived from this research into intervention for children with communicative disabilities. In the most recent funding cycles, our research focus shifted to How does language training alter cognitive competency? That is, What can an organism do following language training that it couldn't do otherwise? or more broadly, What is the role of language in cognition? Answering these questions involves the documentation of the cognitive abilities of language-experienced apes, comparison of these apes' performance with task performance by chimpanzees without language training (including those tested by our scientists as well as those in the literature), examination of what other nonhuman primates (e.g., rhesus monkeys) can do in the absence of language abilities, and comparison of nonhuman pnmates' cognitive abilities to those observed for human adults and children with normal language development. In the present proposal, we continue and significantly expand this tradition, including again the comparison of nonhuman primate behavior to the behavior of children and adults as a research strategy and intervention with specific populations of children and adults in a translational strategy. At the same time, the present programproject represents a significant expansion with respect to nonhuman primate species being studied. With the acquisition of a capuchin monkey colony at the Language Research Center, our capacity is much greater for comparing cognitive competencies across three nonhuman species (with very different brain sizes and developments, very different social structures, and very different documented learning histories). Finally, the present proposal also represents an expansion with respect to number and range of cognitive competencies to be studied, as we propose to test the generality across species of principles denved from the systematic study of learning, perception, attention, executive function, metacognition, categorization, memory, behavioral selfregulation, and problem solving. Given this growth, it was determined that the present proposal was better cast as a new program-project rather than as a continuation of our previous research program.